1. Field of the Invention
The present invention relates to poles, and in particular, to poles used to elevate items to substantial heights, for example greater than 35 feet.
2. Problems in the Art
Many trade-offs exist with respect to the design of poles to elevate items to substantial heights. Examples are strength versus weight; size versus wind load; weight/size versus transportability, handling, and installation ease; and materials versus costs.
Wood poles have substantial strength and are relatively inexpensive. However, they are relatively high in weight and relatively difficult to transport and handle. Likewise, concrete poles have relatively high strength but are also of high weight and are cumbersome to transport and handle.
Additionally, there are other factors, which affect the choice of poles. Examples are the type of item to be elevated; and its size, weight, and function. Another factor is the environment. Will the pole be erected outside or inside? If erected outside, will it experience high humidity or moisture? Will it experience significant winds? Another factor is the purpose of the pole. Is it permanent or temporary?
Tubular steel is a popular choice for such poles. It is relatively high strength and low weight. Through galvanization, it resists rust and corrosion and therefore can be made to be durable for even outside use. Although more costly than wood, for example, its other advantages make it an attractive choice.
Poles greater than 35xe2x80x2 in height, even if made of tubular steel, will still present difficulties. Transportation issues exist. Some poles need to be on the order of 100xe2x80x2 or more tall. Even semi-trailer trucks may not be able to transport such lengths, at least without special and costly permits. Although tubular steel is relatively lightweight, any item of such length is cumbersome to handle.
Additionally, once erected, it is not trivial to conduct maintenance on an item elevated by the pole. A worker many times must be elevated to the top of the pole, which requires costly and complicated equipment.
Attempts have been made to address some of these problems. Poles made and assembled in sections have been tried. Transportation and handling might be easier, but assembly requires some type of relatively complex and time consuming joint between sections.
Another attempt, commonly owned by the owner of the present application, utilizes a tapered tubular steel pole made of sections that slip fit over one another. See, for example, U.S. Pat. No. 5,398,478, incorporated by reference herein. While such a pole has been found to be very effective for certain uses, once installed, it is difficult to disassemble, modify, or move. It therefore has limited flexibility with regard to function.
It is therefore a principal object of the present invention to provide a method and apparatus, which solves or overcomes the problems and deficiencies in the art.
Other features, objects and advantages of the present invention include a method and apparatus for a pole which is:
a. Collapsible, being retractable and extendible.
b. More easily transportable, being smaller in length and compact when in a collapsed position relative to its extended position.
c. Easier to handle and manipulate and install.
d. Extendible to a lockable position.
e. Unlockable to allow retraction.
f. Retains the benefits of tubular steel.
g. Quicker and easier to install and reinstall.
h. Durable.
i. Economical.
j. Flexible regarding uses and functions.
These and other objects, features and advantages of the invention will become more apparent with reference to the accompanying specification and claims.
The present invention includes an elongated pole extendible to substantial heights. A lower end is adapted for mounting to a support. At least first and second pole sections are adapted to move relative to one another so that one nests inside the other in a collapsed or retracted position. The first and second pole sections can telescopically extend from the retracted position to an extended position. A releasable locking member or members can selectably lock the first and second pole sections into the extended position.
A further feature of the invention includes adding additional pole sections having the same attributes. Multiple pole sections can be collapsed so that all pole sections nest in a first pole section but can be telescopically extended. Releasable locking member(s) can be placed to lock each adjacent pair of pole sections. The method according to the invention includes elevating an item by telescopically extending one or more sections of a pole and locking the extended sections in position.